Skeleton form frame for sprue formers



Oct. 29, 1940. c. E. SUMMY I SKELETON FORM FRAME FOR SPRUE FORMERS Original Filed Oct. 1, 1938 In venior A itorneys Patented Oct. 29, 1940 PATENT OFFICE SKELETON FORM FRAME FOR SPRUE FOBMERS Charles E. Summy, laullina, Iowa Application October 1, 1938, Serial No. 232,856 Renewed April 12, 1940 1 Claim.

This invention relates to a skeleton form frame for use with sprue formers, such as those used by dentists, the general object of the invention being to provide a skeleton frame which is to be used instead of the flask or tubular form member now generally used to hold the material around the pattern. This skeleton frame will not interfere with expansion and contraction of the material from which the mold is made, permits the material to be readily placed about the wax pattern and it protects the investment or other material from being broken in handling and lessens the amount of heat required in treating the material. i

This invention also consists in certain other features of construction and 'in the combination and arrangement of the several parts to be hereinafter fully described, illustrated in the accompanying drawing and specifically pointed out in the appended claim. I

In describing the invention in detail, reference will be had to the accompanying drawing wherein like characters denote like or corresponding parts throughout the several views, and in which:

Figure l is a perspective view of the invention. 1

Figure 2 is a top plan view thereof.

Figure 3 is a view showing the invention in use on a sprue former.

Figure 4 is a vertical sectional view through the device.

As shown in this drawing the device comprises a narrow ring l and a plurality of rod-like members 2. While the drawing shows four of these members 2 attached to the ring any suitable number may be used. Each member 2 has its lower end bent outwardly at right angles as shown at 3 and an intermediate part of this bent portion is suitably fastened to the upper edge of the ring so that a part of the portion 3 projects beyond the ring. The upper end of each member 2 is bent at right angles inwardly as shown at 4. The lower edge of the ring I is formed with the notches 5 for facilitating removal of the ring from the channel of the sprue former.

As shown in Figure 3 the ring I is placed in the channel of the sprue former A with the ends of the parts 3 projecting beyond the former so as to hold the device in the casting machine and the bent upper ends 4 extend over the pattern B. Thus the investment or'other material can be readily placed around the pattern and 5 as the members 2 are embedded in this material the device will hold the material in place, the same as the usual flask or tubular form now in general use. However, the skeleton form of the device will not interfere with contraction and expansion of the material while holding the material together around the pattern and it permits the material to be readily placed around the pattern as the material can be pressed in practically all directions to properly engage the pattern; The device also permits the material to be readily handled during the making, heating, and casting and otherwise handling of the mold. Also with the flask or tubular member now in use a high degree of heat is required as the entire tubular member must be heated before the heat reaches the material. Due to the fact that less metal is used in my device-than in the tubular form the investment material can be applied in a drier form than with the ring or tubular member and less heat is required to dry out the material and less time for the heat ing process is required than with the usual tubular member. Also this skeleton device allowing full and unrestricted expansion and contraction of the material will eliminate internal invention will be readily apparent.

It is to be understood that changes may be made in the construction and in the combination and arrangement of the several parts provided that such changes fall within the scope of the appended claim. I

Having described the invention, what is claimed as new is:

An investment'holder for use-on a sprue former of the type having a center dome, a channel surrounding the base of the dome, and an edge flange surrounding the channel, said holder comprising an annular base band adapted to extend into said channel for anchoring in the investment therein, a plurality of upstanding rods on said band having inturned upper ends and forming a cage for holding the investment around a pattern and permitting packing of the same in substantially all directions, said cage fitting at its'lower end around said dome in engagement therewith to center the same relative to the former, said rods having out-turned lower CHARLES E. SUMIMY. 

